Speech-evoked brain activity is more robust to competing speech when it is spoken by someone familiar

Abstract

People are much better at understanding speech when it is spoken by a familiar talker—such as a friend or partner—than when the interlocutor is unfamiliar. This provides an opportunity to examine the substrates of intelligibility and familiarity, independent of acoustics. Is the familiarity effect evident as early as primary auditory cortex, or only at later processing stages? Here, we presented sentences spoken by naturally familiar talkers (the participant’s friend or partner) and unfamiliar talkers (the friends or partners of other participants). We compared multivariate activity in speech-sensitive regions of cortex between conditions in which target sentences were presented alone and conditions in which the same target sentences were presented at the same time as a competing sentence. Using representational similarity analysis (RSA), we demonstrate that the pattern of activity evoked by a spoken sentence is less degraded by the presence of a competing sentence when it is spoken by a friend or partner than by someone unfamiliar; the results cannot be explained by acoustic differences since familiar and unfamiliar talkers were nearly identical across the group. This familiar-voice advantage is most prominent in nonprimary auditory cortical areas, along the posterior superior and middle temporal gyri. Across participants, the magnitude of the familiar-unfamiliar RSA difference correlates with the familiar-voice benefit to intelligibility. Overall, our results demonstrate that experience-driven improvements in intelligibility are associated with enhanced patterns of neural activity in nonprimary auditory cortical areas.Significance statementSpeech is a complex signal, and we do not yet fully understand how the content of a spoken sentence is encoded in cortex. Here, we used a novel approach based on analysing multivariate activity: we compared activity evoked by highly intelligible sentences presented alone and by the same sentences presented with a competing masker. The distributed pattern of activity in speech-sensitive regions of the brain was more similar between the alone and masker conditions when the target sentence was spoken by someone familiar—the participant’s friend or partner—than someone unfamiliar. This metric correlated with the intelligibility of the familiar voice. These results imply that the spatial pattern of activity in speech-sensitive regions reflects the intelligibility of a spoken sentence.

Multivariate functional neuroimaging analyses reveal that strength-dependent face expectations are represented in higher-level face-identity areas

“…4a and b, respectively). As in previous studies 67,84,85 , we used subsections to test our hypotheses about representational similarity across localizer and test runs. Specifically, to evaluate how representational dissimilarity depends on prior strength, we weighted the hypothesized similarity (1) with the three graded levels of expectation strength (i.e., 1, 0.5, 0), (2) the highly expected face (i.e., 1, 1, 0), and (3) the face with the low and high probability (i.e., 0, 1, 0) for the expected faces (Fig.…”

Data-driven multiscale model of macaque auditory thalamocortical circuits reproduces in vivo dynamics

“…The auditory system is involved in a number of crucial sensory functions, including speech processing (Hamilton et al 2021), (Matsumoto et al 2011), (Fontolan et al 2014), (Gourévitch et al 2008), sound localization (Andéol et al 2011), (Carlile, Martin, and McAnally 2005), (Ahveninen, Kopčo, and Jääskeläinen 2014), pitch discrimination (Tramo, Shah, and Braida 2002), (Tramo et al 2005), (Dykstra et al 2012), (Hyde, Peretz, and Zatorre 2008), and voice recognition (Latinus et al 2013), (Holmes and Johnsrude 2021). Aberrations along this pathway can result in a wide variety of pathologies.…”